New Chemistry for You : Summary

1
Summary Rocks and building

• Everything is made up from tiny particles, called
  atoms.
• There are about 100 different types of atoms.
• Groups of 2 or more atoms chemically bonded
  together are called molecules.
• Some substances contain only one type of atom.
  These are elements.
• Elements cant be broken down into simpler
  substances.

AQA C1a.1 Chapters 2 and 9
2
Summary Rocks and building

• If a substance contains more than one type of
  atom, it is a compound.
• The different elements in a compound cant be
  separated easily (they are chemically bonded
  together), unlike the substances in a mixture.
• Chemical changes make new substances, but
  physical changes dont.

AQA C1a.1 Chapters 2 and 9
3
Summary Rocks and building

• Each atom has its own chemical symbol
  e.g. Na sodium and Cl chlorine
• Atoms contain protons, neutrons and electrons.
• Protons are positively charged.
• Neutrons have no charge, they are neutral
• Electrons are negatively charged.
• The electrons orbit the nucleus in shells.
• When atoms bond together, electrons are either
  shared or given and taken.

AQA C1a.1 Chapters 2 and 9
4
Summary Rocks and building

• The Periodic Table arranges the elements in order
  of atomic number.
• Elements with similar properties line up in
  vertical columns. These columns are called
  groups.
• There are 8 groups in the Periodic Table.

AQA C1a.1 Chapters 2 and 9
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Summary Rocks and building

• We can show chemical changes (called reactions)
  by equations.
• We use either words or chemical symbols (and
  formulas).
• Symbol equations must be balanced. New atoms are
  not created or destroyed in a chemical reaction.
  The total mass of reactants is always equal to
  the total mass of products.
• State symbols - (s), (l), (g) or (aq) - can give
  us extra information about a reaction

AQA C1a.1 Chapters 2 and 9
6
Summary Rocks and building

• Calcium carbonate (CaCO3) is mainly found in
  nature as limestone, chalk and marble.
• It is broken down by heat (thermal
  decomposition), to give calcium oxide and carbon
  dioxide.
• Calcium oxide (quicklime) reacts with water to
  form calcium hydroxide (slaked lime).
• This can be used to neutralise acidic soil.

AQA C1a.1 Chapters 2 and 9
7
Summary Rocks and building

• Cement is made from crushed limestone and clay in
  a rotary kiln.
• Glass is made by heating limestone, sand and
  sodium carbonate (soda).

AQA C1a.1 Chapters 2 and 9
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